A turbo-molecular pump, which magnetically levitate a rotor using a superimposed sensorless magnetic levitation device, is adapted to superimpose a carrier having a frequency higher than a frequency band for magnetic levitation control on the driving current of an electromagnet for magnetic levitation and to measure a distance between the electromagnet and the rotor based on the voltage, current, or the like of the modulated carrier signal (e.g., refer to Patent Document 1).